Terminology & functionality

L2G3IS

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DocID024950 Rev 3

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Terminology & functionality

2.1

Sensitivity

An angular rate gyroscope is a device that produces a positive-going digital output for

counterclockwise rotation around the sensitive axis considered. Sensitivity describes the

gain of the sensor and can be determined by applying a defined angular velocity to it. This

value changes very little over temperature and time.

2.2

Zero-rate level

The zero-rate level describes the actual output signal if there is no angular rate present. The

zero-rate level of highly accurate MEMS sensors is, to some extent, a result of stress to the

sensor and therefore the zero-rate level can slightly change after mounting the sensor on a

printed circuit board or after exposing it to extensive mechanical stress. This value changes

very little over temperature and time.

2.3

Synchronous reading

On the L2G3IS the angular rate data can be retrieved using a synchronous read. This

functionality is recommended to improve the sensor performance.

To perform a synchronous read when using the SPI interface, the REG_EN bit in

CTRL_REG1 (0Bh) has to be set to ‘1’. Then the DRDY_EN bit in CTRL_REG4 (15h) has to

be set to '1' in order to enable the data ready interrupt on the DRDY pin (refer to Figure 5).

To properly perform a synchronous read, the angular rate data have to be read every time

the DRDY pin goes low.

2.4

Temperature sensor

To retrieve the temperature data, the gyroscope has to be in sleep mode (PW<1:0> bit in

CTRL_REG1 (0Bh) set to ‘10’), the REG_EN bit in CTRL_REG1 (0Bh) has to be set to ‘1’

and the temperature sensor can be enabled by setting the TEMP_EN bit to ‘1’ in

CTRL_TEMP (20h).

The temperature data can be retrieved from the OUT_TEMP (26h) register, as two’s

complement data in 8-bit format left-justified. The output of the temperature sensor is 0 at

25 °C.

Once the temperature data have been acquired, the temperature sensor has to be turned off

to restart the acquisition of the angular rate data. The TEMP_EN bit in CTRL_TEMP (20h)

has to be set to ‘0’ and the gyroscope operative mode has to be changed to normal mode

(PW<1:0> bit in CTRL_REG1 (0Bh) set to ‘11’).